JP2757220B2 - Fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a fuel injection device for an internal combustion engine.

(Prior art) Two-cycle engines have been developed by various manufacturers in response to demands for smaller, higher-output, lower fuel consumption, and lower vibration of the engine. However, a fuel injection device suitable for a two-cycle engine is still insufficient. Since it cannot be said that the requirements are satisfied, the current situation is that a conventional four-cycle fuel injection device is changed to two-cycle fuel injection.

FIG. 5 shows an apparatus for supplying fuel to an engine proposed in Japanese Patent Application Laid-Open No. 62-93481, in which fuel is supplied from a fuel tank 35 to a known injector 30 via a pump 36. In addition, high-pressure air is supplied from an air source 37 to the chamber 32, and the fuel metered in advance from the injector 30 is injected into the chamber 32. Then the solenoid
When the valve 31 is operated and the valve 33 is opened, fuel is injected from the injection hole 34 together with the high-pressure air.

(Problem to be Solved by the Invention) In the conventional apparatus shown in FIG. 5, a step of injecting fuel into the high-pressure air chamber 32 by activating a solenoid of a fuel measuring section of the injector 30 and activating another solenoid 31 And the process of injecting fuel to the outside. However, in such a method, since two solenoids are provided, not only the main body becomes large,
There was a disadvantage that the control method was complicated.

SUMMARY OF THE INVENTION The present invention provides a single-solenoid fuel injection device suitable for a two-cycle engine.

[Configuration of the invention]

(Means for Solving the Problems) In order to solve the above problem, the present invention is directed to a bobbin on which a coil is wound, wherein a core is inserted into and fixed to one side of a center hole of the bobbin, and the other side of the center hole of the bobbin is spaced from the core. Armature is arranged in,
A mixing chamber communicating with the high-pressure air passage is formed in the core, and a fuel injection nozzle is fixed to the core. The fuel injection nozzle is disposed in the mixing chamber, and is urged in a direction to close an outlet of the injection nozzle by a first spring. And a movable valve seat having a fuel passage communicating with the mixing chamber, a magnetic chamber for providing a fuel chamber in the armature, and opening and closing a fuel passage of the movable valve seat between the armature and the movable valve seat. And a second spring and a third spring having a smaller spring force than the first spring on the mixing chamber side for urging the metering valve in a direction to close the fuel passage. This is a means for solving the problem.

The present invention also has an annular member fixed to the movable valve seat while attaching a permanent magnet having the same diameter as the metering valve to a side outer peripheral surface of the armature side of the metering valve. The armature is in contact with the armature, and is used as a means for solving the problem.

(Operation) When a low current is applied to the coil, the armature does not move, and the metering valve is pulled by the armature and moves against the second spring on the fuel chamber side, thereby opening the fuel passage of the movable valve seat, and The fuel in the chamber flows into the mixing chamber and is measured. Next, when a high current is applied to the coil, the metering valve is first drawn by the armature and moves to open the fuel passage, and the armature is drawn by the core and moves while keeping this passage open. Since the metering valve opens instantaneously, the amount of fuel re-metered at this time is very small and constant. This opens the fuel injection nozzle by pushing the movable valve seat through the metering valve,
A mixture of high-pressure air and fuel in the mixing chamber is injected.

In the second embodiment, when a low current is applied to the coil, the metering valve is pulled by the armature and moves to open the fuel passage of the movable valve seat, and the fuel in the fuel chamber flows into the mixing chamber. Next, when a high current in the opposite direction is applied to the coil, the armature is pulled by the core and moves, but prior to this, the permanent magnet repels and the metering valve moves to the opposite side of the armature to move the fuel passage. When closed, the movable valve seat is moved by being pushed by the armature, the fuel injection nozzle is opened, and the air-fuel mixture in the mixing chamber is injected from the tip of the injection nozzle.

(Embodiments) The present invention will be described below with reference to the embodiments in the drawings.
FIG. 2 and FIG. 2 show first and second embodiments of the present invention.

First, in FIG. 1, reference numeral 1 denotes a magnetic metering valve, and reference numeral 2 denotes a movable valve seat which is disposed coaxially with a ball 13 fixed to the metering valve 1 so as to be able to come and go. A rod 14 is fixed to the metering valve 1, and the ball 13 is pressed against the movable valve seat 2 by the second spring 4 via the rod 14 to close the fuel passage 11 provided in the movable valve seat 2. The strength of the second spring 4 can be adjusted by an adjuster 10 which is screwed into an inlet of a fuel chamber 5 formed at the center of the armature 8, and the metering valve 1 is always in the second position. A gap 15 is formed between the spring 4 and the armature 8. The armature 8 is slidably inserted into one side of the center hole of the non-magnetic bobbin 16 around which the coil 7 is wound, and the core 9 similarly fitted and fixed to the other side of the center hole of the bobbin 16. A gap 17 is provided therebetween, and a side end thereof is in contact with a cover 19 having a fuel supply hole 18. A hole is also provided at the center of the adjuster 10 to allow the fuel supply hole 18 to communicate with the fuel chamber 5.

The core 9 fits into the casing 20 and is fixed.
A hole 21 in which the metering valve 1 is fitted and a mixing chamber 6 communicating with the hole 21 are provided at the center, and a base of a fuel injection nozzle 22 is fitted and fixed in the mixing chamber 6. A fuel injection passage 23 is provided at the center of the nozzle 22 in communication with the mixing chamber 6, and a rod 24 having a check valve 12 at the tip is inserted into the passage 23, and a rear portion of the rod 24 is provided. Is inserted into the movable valve seat 2 to a position where the fuel passage 11 and the hole 11a of the movable valve seat 2 are not closed, and is caulked and fixed to the thin portion of the movable valve seat 2. The check valve 12 is always the first valve. The spring 3 is biased to close. The first spring 3 is provided with the nozzle 22
The movable valve seat 2 is urged to be pressed against the ball 13. Also the first
The spring force of the spring 3 is set to be larger than that of the second spring 4, and the metering valve 1 is connected to the spring 3 so that a gap 15 is formed between the spring 3 and the armature 8 by the second spring 4. The spring force of No. 4 is adjusted. Reference numeral 25 denotes a diaphragm, the outer peripheral portion of which is clamped and fixed between a core 9 and a magnetic intermediate holder member 30 in contact with the fuel injection nozzle 22, and an inner peripheral portion of which is an outer peripheral surface of the movable valve seat 2. Are fixed to each other by fitting a holder member 29 thereto. Therefore, the mixing chamber 6 is separated from the fuel chamber 5 by the diaphragm 25. Further, the fuel passage 11 communicates with the mixing chamber 6 through a hole 11a. 26 is a seal member and 27 is an air supply port which is always in communication with the mixing chamber 6. 31 is a third spring.

Next, the operation will be described. High-pressure air that is pressure-fed by an air pump (not shown) is constantly supplied to the mixing chamber 6 through the air supply port 27. FIG. 1 shows a state when the coil is energized.

Measuring Step When a low current is applied to the coil 7, the armature 8 does not move and only the small measuring valve 1 is pulled to the armature 8 because the spring force of the first spring 3 is larger than that of the second spring 4. Then, it moves against the second spring 4. Therefore, since the ball 13 is separated from the inlet of the fuel passage 11, the fuel supplied from the fuel supply hole 18 to the fuel chamber 5 through the center hole of the stopper 10 is removed from the inner peripheral surface of the hole 21 of the core 9 and the The fuel enters the fuel passage 11 through the space between the outer surfaces, and further flows into the mixing chamber 6 through the hole 11a.

Injection Step Next, when a high current is applied to the coil 7, first, the metering valve 1
When the armature 8 is pulled by the armature 8 and moves against the spring 4, the fuel passage 11 is instantaneously opened, and the armature 8 is sucked by the core 9 and moves while being opened. Therefore, since the movable valve seat 2 is pushed against the first spring 3 via the ball 13 of the metering valve 1, the rod 24 is also pushed out and the check valve 12 is opened, so that the mixing chamber 6 passes through the passage 23 around the rod 24. The mixture of the high-pressure air and the fuel that has flowed out up to this point is injected from the tip of the opened fuel injection nozzle 22. The fuel injection amount at this time is an added value of the amount measured by the low current operation and the amount (fine-quantitative) added by the instantaneous opening of the metering valve 1 in the high current operation region.

FIG. 3 shows a solenoid drive current pattern in the case of FIG. 1. First, a small current is supplied to the coil 7 to move the seal valve 1, thereby supplying fuel to the mixing chamber 6 and measuring the fuel. When a large current flows through the armature 7, the armature 8 moves and pushes the fuel injection rod 24 through the metering valve 1 and the movable valve seat 2 to open the check valve 12, and the current value in the state of injecting fuel is increased. Shows the level and energizing time.

Next, FIG. 2 shows a second embodiment. The difference from FIG. 1 is that the metering valve 1 is provided on the peripheral surface of the end of the metering valve 1 on the spring 4 side.
An annular permanent magnet 28 having substantially the same outer diameter as that of the movable valve seat 2 is fixed, and a thin annular portion of the non-magnetic diaphragm holder member 29 fitted and fixed to the movable valve seat 2 is extended to abut on the armature. The point and the third spring are eliminated.

Next, the operation will be described with reference to FIG. FIG. 2 shows a state in which the coil is not conducted, similarly to FIG. First, when a low current is applied to the coil 7 for a predetermined time, the metering valve 1 is pulled by the armature 8 and moves, so that the fuel passage 11 is opened and the fuel chamber 5 is opened.
The fuel inside flows into the mixing chamber 6. Next, when a high current in the opposite direction to the low current is applied to the coil 7, the armature 8 is pulled by the core 9 and moves. Before this, the permanent magnet 28 is attached to the metering valve 1; The metering valve 1 repels the armature 8 and separates from the armature 8 to close the fuel passage 11 so that fuel is not supplied into the mixing chamber 6 unlike the case of FIG. When the armature 8 is pulled by the core 9 and moves as described above, the fuel injection rod 24 is pushed through the holder member 29 and the movable valve seat 2 to open the check valve 12, and the high pressure in the mixing chamber 6 is increased. Check valve for air-fuel mixture 12
Inject from the part.

FIG. 4 shows a solenoid drive current pattern in the case of FIG. 2, in which fuel is metered with a low current as a minus current, but a high current is a plus current, so the fuel passage is closed by a metering valve. It shows the current value level polarity and energizing time in a state where the fuel is injected without re-metering.

〔The invention's effect〕

As described in detail above, the present invention is configured, and by flowing a low current through the coil, the metering valve is moved to cause a predetermined fuel to flow into the mixing chamber, and then a high current is passed through the same coil, so that the armature is used. By pressing the movable valve seat and opening the fuel injection nozzle, the air-fuel mixture can be injected. Thus, in the present invention, it is possible to reduce the size because only one coil is required as compared with the case where two solenoids are separately driven as in the related art. In addition, since the drive circuit of the fuel injection device can be simplified and fuel is injected with high-pressure air,
The atomization of the fuel is promoted, and the combustion is improved. In addition, when a permanent magnet is attached to the metering valve to make the low current and the high current reverse to each other, it can be said that the fuel can be measured more precisely without performing the fuel measurement again in the injection process of flowing the high current. It works.

[Brief description of the drawings]

1 and 2 are front sectional views showing a fuel injection device according to first and second embodiments of the present invention, and FIGS. 3 and 4 are explanatory diagrams showing current patterns in FIGS. 1 and 2. FIG. 5 is a partial cross-sectional front view showing an example of a conventional fuel injection device. Description of main parts in the drawing 1... Metering valve, 2... Movable valve seat 3... 1st spring 4... 2nd spring 5... Fuel chamber 6. … Armature, 9… Core 10… Adjuster, 11… Fuel passage 12… Check valve, 13… Ball 14… Rod, 15, 17… Gap 16… Bobbin, 18… Fuel supply hole 19 cover 20 casing 22 fuel injection nozzle 23 fuel injection passage 24 rod 25 diaphragm 27 air supply port 28 permanent magnet 29 holder member 30 …… Intermediate holder member

Claims (2)

(57) [Claims] 1. A core is inserted and fixed in one side of a center hole of a bobbin around which a coil is wound, and an armature is arranged on the other side of the center hole of the bobbin with a gap from the core. Forms a mixing chamber communicating with the high-pressure air passage, fixes the fuel injection nozzle, and is disposed in the mixing chamber;
A movable valve seat urged by a first spring in a direction to close an outlet of the injection nozzle and having a fuel passage communicating with the mixing chamber; a fuel chamber provided in the armature; A magnetic metering valve for opening and closing the fuel passage of the movable valve seat is provided between the movable valve seat and the first spring on the mixing chamber side for urging the metering valve in a direction to close the fuel passage. A fuel injection device comprising a small second spring and a third spring. 2. The fuel injection device according to claim 1, wherein a permanent magnet having substantially the same diameter as the metering valve is attached to an outer peripheral surface of an armature side of the metering valve, and is fitted and fixed to the movable valve seat. A fuel injection device having an annular member, the annular member being in contact with the armature.